The below-noted specific pyridazinone compound in the present invention is known to have superior platelet aggregation inhibitory effect, cardiotonic effect, vasodilating effect, anti-SRS-A (Slow Reacting Substances of Anaphylaxis) effect, thromboxane A.sub.2 synthase inhibitory effect and the like (JP-B-7-107055, JP-A-7-285869), and is a drug expected to be an antiplatelet agent and the like.
However, there has not been any report on the effect of the pyridazinone compound on angiogenesis.